Fix sign warning in ocl.c

miner.h

@@ -379,7 +379,7 @@ struct cgpu_info {
 #ifdef USE_SCRYPT
 	int opt_lg, lookup_gap;
 	size_t opt_tc, thread_concurrency;
-	int shaders;
+	size_t shaders;
 #endif
 	struct timeval tv_gpustart;
 	struct timeval tv_gpumid;